1. Field of the Invention
This invention relates to calendering systems. Such structures of this type, generally, employ the use of hard or soft nips to provide excellent smoothness without gloss mottle.
2. Description of the Related Art
It is well known in calendering systems, particularly heated soft roll calendering systems, to employ a soft roll at high pressures. Exemplary of such prior art is U.S. Pat. No. 4,624,744 ('744) to J. H. Vreeland, entitled "Method of Finishing Paper Utilizing Substrata Thermal Molding". While the '744 patent does achieve calendering, the use of the high nip pressures, namely, pressures above 2000 psi, reduce the bulk of the paper. Consequently, such use of a calendering device is, typically, employed when calendering fine papers. Consequently, a more advantageous calendering system, then, would be employed if calendering could be done at lower nip pressures in order to reduce bulk loss.
It is apparent from the above that there exists a need in the art for a calendering system which is able to calender as well as the known calendering systems, while providing excellent smoothness without gloss mottle (an uneven pattern of gloss or reflectance), but at the same time is able to calender at lower nip pressures.
It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.